Syringes have traditionally been used in the medical industry to deliver medicaments or to draw biological fluids from a patient. Today, syringes are often prefilled and are used to store medicaments prior to their delivery. Conventionally, a male and female thread or a “push-in” method is used to physically insert a plunger rod into the piston. However, the “push-in” method often requires a high force to insert which results in plunger translation within the barrel if insertion forces are higher than plunger break forces. The male and female thread insertion method causes undesirable plunger rotation within the barrel when the plunger rod reaches the termination of the thread section. Eliminating plunger translation and rotation is desirable to drug manufacturers and is a well-known concern in the pharmaceutical industry because plunger movement within the barrel can potentially breach a sterile barrier of a drug or biologic, thus rendering the syringe useless.
Additionally, syringes typically require the use of silicone oil for rod insertion into the plunger. However, some drug formulations and biologics are sensitive to the presence of silicone oil. The presence of silicone oil anywhere in the plunger system, including the plunger rod may cause leeching or migration of silicone oil to a drug product.
Thus there exists a need in the art for a syringe that has an improved ease of use, that reduces or eliminates plunger translation and rotation, simplifies manufacturing, and eliminates potential leeching and migration of silicone oil.